Shrinkproofing of protein fibers with polyalkyleneimines



, 2,925,317 Patented Feb. 16, 96Q

SHRINKPROOFING OF PROTEIN FIBERS WITH 7 POLYALKYLENEIMINES Joseph E.Moore, Pinole, and Clay E. Pardo, Jr.', Albany,

Califl, assignors to the United States of America as represented by theSecretary of Agriculture No Drawing. Application September 18,1956Serial N- 610,690

. 4 Claims. c1. ti-127.6) I (Granted under Title 35, US. Code (1952),sec. 266) A non-exclusive,irrevocable, royalty-free license intheinvention herein described, throughout the world for all purposes ofthe United States Government, with the powerto grant sublicenses forsuch purposes, is hereby granted to the Government of the United Statesof America.

This invention relates to processes for shrinkproofing and felt-proofingproteinaceous fibers, especially wool. In particular, the invention isconcerned with procedures wherein the fiber is treated with a preformedpolyalkyleneimine and then cured withthe application of heat whereby toproduce a fiber which exhibits a marked resistance to shrinkage ascompared with the original fiber. Further objects and advantages of theinvention will be obvious from the description herein.

It is well known that laundering causessevere shrinkage to woolentextiles. This technical disadvantage seriously restricts theapplications of wool in the textile industry and much research has beenundertaken to modify the natural fiber to improve its shrinkageproperties'. In general, known methods of treating wool to imine;2,2-dimethy1-ethylene imine; 2,2,3-trimethylethylene imine;2,2-dimethyl-3-propyl-ethylene imine; cyclohexyl fethylene imine; phenylethylenimine, etc.

These compounds, as well known in the art, can be prepared, for.example, by polymerizing the alkylene imine in the pres.- ence of acatalyst such as sodium bisulphate, hydrochloric acid, sulphuric acid,acetic acid, hydrogen peroxide, and so forth. Generally, it is preferredto use the polyalkylene imines which are at least partially soluble inwater.

The solution applied to the protein fibers inaccordance with thisinvention contains as its principal ingredient the preformedpolyalkylene imine. The concentration of this agent in the solution isnot critical and may be, for

example, as low as 0.1% or 'as high as 10%. Usually water is used as thesole solvent for the imine. However, the solution may contain both waterand a watersoluble organic solvent such as methyl alcohol, ethylalcohol, propyl alcohol, isopropyl a1cohol,'any of the isomeric butylalcohols, acetone, etc. The use of a mixed solvent of water and alcoholor ketone is particularly useful where the particular imine chosen isnot completely water-soluble.

' In order to achieve a maximum shrinkproofing effect, it is necessaryto control the pH of the polyalkylene imine solution which is applied tothe protein fiber. "Acid conditions are not suitable as they preventproduction of a shrink-resistant product. To achieve best results, thetreating solution should be preferably alkaline,

improve its shrinkage characteristics have the disadjust the pH to theabove-cited range,'one may add to the treatment solution an acid oralkaline substance as needed. To decrease the pH, one may add agentssuch as sulphuric acid, hydrochloric acid, phosphoric acid,

-sodium bisulphite, monosodium phosphate, etc. To inpreformedpolyalkyleneimine, the shrinkage characteris almost completelyshrinkproof under usual launderingprocedures. The reason for theeffectiveness of the process'of this invention cannot be explained on ascienlcrease the pH one may add such agents as sodium carbonate,trisodium phosphate, borax, potassium carbonate, tetrasodiumpyrophosphate, andso forth.

After the wool has been impregnated with the imine .solution, it issubjected to a heat curing operation. This simply involves subjectingthe textile material to a temperature from about 75 to about 150C. topromote reaction between the imine and the wool whereby the iminebecomes bonded to the protein molecule and can tific basis. However, itis believed that the polyalkylene imine actually reacts with the wool,forming part of the formed by immersing the wool in an excess of thesolu- 7 tion or by applying the solution by spraying, brushing or otherconventional application techniques. To assist in wetting the wool withthe solution, it may be run through padding rolls or the like.

Although polyethylene imine is the preferred shrinkproofing agent ofthis invention, one can use any other polyalkylene imine. Typicalexamples are the polymers of: propylene imine; 1,2-butylene imine;2,3-buty1ene no longer be removed by washing. The time of cure will varydepending on the temperature selected, the chemical nature of the fiberbeing treated, the degree of shrinkproofing desired, and so on. Ingeneral, a cure time of about 15 min. to about 2 hours may be used. Apreferred curing operation involves heating for about 30 minutes to onehour at C.

After the textile material has been cured it may be Washed with water orlaundered to remove excess imine which'is not actually bonded to theprotein molecules. The textile material is then dried in the usualmanner and is ready for use.

The proportion of polyalkylene imine bonded to the protein fiber may bevaried widely by varying the concentration of polyalkylenimine in thetreatment solution taken up by the fibrous material. Usually theseconditions are so chosen that the fiber takes up about from 0.1% to 10%of its weight of polyalkylene imine. In general the larger theproportion of imine taken up by the fiber, the greater will be theshrinkage protection afiorded. It is also obvious that the degree ofshrinkproofing attained will vary depending on such factors as theoriginal characteristics of the fiber, the type of polyalkylene iminechosen and so forth. In any particular situation the fiber may besubjected to pilot experiments, applying different proportions of thechosen polyalkylene imine and selecting the conditions which give thedesired degree of shrinkproofing.

The process. of. this invention is particularly adapted for thetreatment of wool but may also be applied to other proteinaceousfiberssuch as mohair, fibers from fleece-bearing animals other thansheep and goats, animal hair, silk, fibers made from proteins such aszein,.casein, peanut protein, keratin, etc. The proteinaceous fiber maybe in the form of actual fibers or may be in the form of threads, yarns,woven or knitted materials, garments, etc.

The invention is further demonstrated by the following example which isgiven onlyby way of illustration but not limitation.

EXAMPLE An aqueous solution was prepared containing of polyethyleneimine (molecular weight about 20,000 to 30,000). The solution had a pHof 11.3.

Samples of woolen cloth were immersed in the solution and the cloth wasrun through padding rolls to assist in wetting it with the treatmentsolution. The cloth samples picked up about 120% of their weight of thesolution.

The cloth samples were then placed in an oven where they were subjectedto a temperature of 120 C. One lot of the samples was subjected to thisheat for 30 minutes, another lot for 60 minutes.

The cured cloth samples were weighed to determine the uptake ofpolyethylene imine. The shrinkage characteristics of the cloth sampleswere determined 'by subjecting them to a laundering operation in whichthe cloth was violently agitated in a 0.5% solution of sodium oieate at40 C. with a cloth to solution ratio of 1:50, the area of the clothbeing measuredbefore and after laundering. With this method oflaundering, untreated cloth samples gave an area shrinkage of 36%.

Also, samples of the cloth which had been subjected to the abovepolyethylene imine treatment and curing were washed for 2 hours inrunning hot (55 C.) water. After'this washing treatment the samples weredried and the residual polyethylene imine content was determined as wellas shrinkage by the above laundering treatment.

The results obtained are set forth in the following table:

Properties of woolen cloth impregnated with 5% solution ofpolyethyleneimine and cured at 120 C.

Sample A B Curing time at 120 0., minutes l 30 PROPERTIES BEFORE HOTWATER EXTRACTIQN Uptake of polyethyleneimine, Percent 3. 62 4. 25 AreaShrinkage, Percent zero zero PROPERTIES AFTER WATER EXTRACTION Uptake ofpolyethyleneimine, Percent 3. 49 2. 25 Area.Shrinkage, Percent 1. 88vzero take of polyethylene imine was 0.95% and the area shrinkage afterlaundering was 19.9%.

Having thusdescribed the invention, what-is claimed 1. A process forshrinkproofing protein fibers-which comprises impregnating the proteinfiber with an aqueous alkaline solution, having a pH about from 9-to 11,containing a preformed polyethylene imine having-a molecular weight ofabout from 20,000 to 30,000, and curing the impregnated protein fiber ata temperature from about C. to about 150 C.

2. A process for shrinkproofing wool which comprises impregnating woolwith an aqueous alkaline solution, having a pH about from 9 toll,containing a preformed polyethylene imine having a molecular weight ;ofabout from 20,000 to 30,000, and curing the impregnated =wool at atemperature-from about 75 C. to about 150 :C.

3. The process of :claim 2 wherein the solution of preformedpolyethylene imine has a pH of about ll.

4. The. process of claim'2 wherein :the impregnated wool is cured atabout C. for about onehour.

References .Cited in the file of this patent UNITED STATES PATENTS

1. A PROCESS FOR SHRINKPROOFING PROTEIN FIBERS WHICH COMPRISESIMPREGNATING THE PROTEIN FIBERS WITH AN AQUEOUS ALKALINE SOLUTION,HAVING A PH ABOUT FROM 9 TO 11, CONTAINING A PREFORMED POLYETHYLENEIMINE HAVING A MOLECULAR WEIGHT OF ABOUT FROM 20,000 TO 30,000, ANDCURING THE IMPREGNATED PROTEIN FIBER AT A TEMPERATURE FROM ABOUT 75*C.TO ABOUT 150*C.